The incident happened at judt after 11.30am today at the Whitburn Post Office at North Guards in Whitburn.

A man went into the shop with a firearm, although police say they do not yet know if the weapon was real or imitation.

Staff were left shocked and shaken but no-one was injured.

The robber remains at large.

Chief Insp Michael Barton, of Northumbria Police's South Tyneside Area Command, said: "This was obviously distressing for those in the shop but I'd like to reassure people that an active investigation is ongoing to trace the man involved.

"Officers are working to establish what happened and I'd urge anyone with information to contact police as soon as possible.

"This is an unusual offence for this area and additional patrols are taking place in the area, anyone with concerns should speak with a local officer."

Anyone with information is asked to contact Northumbria Police on 101 ext 69191, or Crimestoppers anonymously on 0800 555 111.